Overview of Visible Human® based applications at CIeMed

R. Mullick, H. T. Nguyen, Y. P. Wang, J. K. Raphel, and R. Raghavan

Center for Information-enhanced Medicine
Institute of Systems Science,
National University of Singapore, SINGAPORE-119597
Email: rakesh@iss.nus.sg

ABSTRACT

 The Center for Information-enhanced Medicine (CIeMed) has been actively involved in the analysis, visualization, and development of applications based on the Visible Human(TM) dataset. In this paper we summarize our efforts to explore this vast dataset. Our projects include complete segmentation and labeling, direct volume rendering for the entire RGB-volume, real-time catheter simulation using the dataset as a virtual patient, and 2D/3D network based anatomy atlases.

HUMAN
ANATOMY
VISUALIZATION

 The human anatomy visualization project within CIeMed has segmented and labeled the Visible Human(TM)(VH) male dataset into over 300 tissues and organs. This task has been achieved by applying semi-automatic and manual volume segmentation methods to the VH cyro-section data and the registered CT data. An effort to depict these labeled regions, using color, is presented in Figure 1(a).
VHD Female Head
VHD Female Heart
VHD Male Thorax
VHD Male Pelvis

Figure 1: (a) Segmented Visible Human male Data; (b) Full body translucent RGB
Rendering; and (c) Interactive RGB volume rendering environment.

 Furthermore, we have developed a methodology to RGB volume render the entire photo volume using only limited memory systems. This approach, Partitioned Volume Rendering [1 -2] based on a divide-and-conquer algorithm, allows selective translucent visualization of various tissues, organs and systems of the human anatomy and their inter-relationships [Figure 1(b)]. An interactive software environment [Figure 1(c)] allows the user to define the numerous parameters for visualization and to create an animation of the same by varying these parameters using key-frames. CIeMed has also developed Vortex, an interactive volume rendering approach using hardware-based 3D texture mapping. Vortex offers real-time translucent viewing [Figure 2(a)] and perspective fly-through capabilities.

Using these technologies, CIeMed and Alex Tsiaras with Time-Warner, are producing a comprehensive educational study of the human body, understandable and appealing to the lay public and the medical community.

daVINCI:
VIsual Navigation of
Catheter Insertion

 daVinci is a real-time simulation prototype for vascular catheterization procedures. It allows interventional radiologists and students to learn and rehearse difficult navigational tasks for intravascular procedures. daVinci also allows device manufacturers to design and test catheter and guidewire shapes and specify their physical properties.
Cath. Navigation
 CIeMed has used the Visible Human dataset as a virtual patient for the navigational and visual needs of this simulator. The primary arterial vasculature was extracted from the VH photo data. This primary structure served as a roadmap for extending the arterial model by addition of secondary and tertiary networks from other scanned data. A physical model based on this vasculature is used for real-time computation in daVinci [3]. The final vasculature [Figure 2(b)] and the intravascular devices (catheter, guidewire, etc.) are registered to x-ray projection views of the Visible Human CT volume to offer realistic fluoroscopic images and controls (rotate, translate, magnify) as observed in a Catheterization Laboratory.

 Figure 2: (a) Interactive volume rendering using 3D texture mapping; and (b) Fluoroscopic view (using CT data) with vasculature and catheter highlighted.

INTERACTIVE
INTERNET
ATLASES

 The Interactive Internet Atlases, an extension of [4], are based on a Producer Consumer Observer model with the atlas producer generating the data set, atlas consumer providing the rendering and atlas observer capturing user's interactions.
Figure 3: (a) Java Applet to view Labeled VH Data. (b) Interactive 3D viewing of the VH male cortex over Internet using VRML and
SGI Webspace.

 Various architectures which trade off the communication, computation and interactivity are possible within this model. For example, applications such as interactive 2D navigation of the atlas data, the atlas producer acts as a data server for the atlas requests generated by the client applets [Figure 3(a)]. In situations where 3D rendering capabilities are required, the atlas producer is required to generate data sets corresponding to the given orientation. This results in increased communication costs and require specialized servers to handle multiple rendering requests from clients. An alternative is to equip the applets with the ability to handle VRML and retain the architecture similar to the 2D atlas [Figure 3(b)].

ACKNOWLEDGMENTS

 The authors wish to thank Solaiyappan Meiyappan for the development of Vortex, Ng Yew Choong for coding the Java applets, Ms. Jin Xiaoyang and all the students from the National University of Singapore involved in the Human Anatomy Visualization project for their role in segmenting the dataset. We would also like to thank our collaborators Alexander Tsiaras, Anatomical Travelogue, and Dr. Jim Anderson, Johns Hopkins University.

REFERENCES

 1. H. T. Nguyen and R. Srinivasan, ``PaVe4-16: A Distributed Volume Visualization Technique,'' TR94-135-0 Tech. Rep., Inst. of Systems Science, National University of Singapore, Singapore, 1993.
2. R. Mullick and H. T. Nguyen, ``Visualization and Labeling of Visible Human(TM) Dataset: Challenges & Resolves,'' Proceedings of the 1996 Conference on Visualization in Biomedical Computing, Hamburg, Germany, Springer-Verlag, pp 75-80, 1996.
3. C. K. Chui, H. T. Nguyen, Y. P. Wang, R. Mullick, R. Raghavan, and J. Anderson,, ``Potential Field of VHD Vasculature for Real-Time Computation in daVinci,'' Sub. to the First Visible Human Conference, Bethesda, MD, 1996.
4. J. Raphel, R. Raghavan, and W. Nowinski, ``Interactive Internet Brain Atlases in Java,'' Sub. to the 2nd Intl. Conference on Functional Mapping of the Human Brain, Boston, 1996.